A high-power laser (HPL) system images, tracks and projects high power coherent light to a desired aimpoint on a target object. Typically, passive tracking is sufficient and employed for simplicity. The sun can illuminate a target or its very own heat signature can be used for the tracking system. However, often there is not enough sunlight, the target is cold, or it is at the same temperature as the environment. Thus, active illumination is very often required to sufficiently image and track the target.
In conventional expedients, a track illuminator (TILL) simply shines on a portion of or the entire target that is to be followed or tracked. In a car tracking application, the TILL can be deployed to illuminate the front bumper while the track camera images the reflection of the laser. An algorithm configures a processor to drive a steering mirror and uses the image to track the target car. One difficulty of imaging a target with the HPL itself, is the HPL scatter generated by the HPL system's own optics, and by the atmosphere in the target path. This scatter is usually larger than the return from the target and thus blinds the track sensor from seeing the proper track point. For this reason, TILLs are either positioned outside the imaging path and/or the laser is pulsed. This permits the system to determine a range to the target by timing the round trip of the light, and it allows the track camera to look at the target while the TILL is turned off and not blinding the camera. However, the use of a separate TILL adds size, weight, and increases the complexity of the optic coatings in the optics train and telescope.
Thus, it would be advantageous to provide a HPL system that utilizes the HPL itself to enable illumination and tracking of the target by switching off the high-power coherent light for prescribed time intervals during which the camera can track the target over a shared optical path.